Information 2013, 4, 398-410; doi:10.3390/info4040398 OPEN ACCESS information ISSN 2078-2489 www.mdpi.com/journal/information Article Empirical Analysis on Evolution and Small World Effect of Chinese Enterprise-Enterprise Patent Cooperation Network: From the Perspective of Open Innovation Chunxia Ye 1, Xiang Yu 1,* and Wei Li 2 1 School of Management, Huazhong University of Science and Technology, Wuhan 430074, China; E-Mail: [email protected] 2 Wenzhou Entry-Exit Inspection and Quarantine Bureau of China, Wenzhou 325003, China; E-Mail: [email protected] * Author to whom correspondence should be addressed; E-Mail: [email protected]; Tel.: +86-027-8675-3432; Fax: +86-027-8675-3432. Received: 16 August 2013; in revised form: 11 October 2013 / Accepted: 24 October 2013 / Published: 28 October 2013 Abstract: The patent cooperation network which enterprises join is a very important network platform for enterprises’ open innovation. However, very limited work has been done to empirically investigate the dynamic change process of the network in China. To address this issue, this paper analyzes dynamic change process of cooperation network of enterprises and the small-world effect of the biggest subgroup according to the data of 36731 items of cooperative patents between enterprises from 1985 to 2010 published by the State Intellectual Property Office of China. A conclusion can be drawn from the analysis results that the biggest subgroup has the characteristics of small-world effect, but the overall network structure also has some defects, which limit the development of open innovation. For the first time, suggestions on open innovation strategies are put forward to provide theoretical reference for both the government and enterprises. Keywords: patent cooperation network; information mining; open innovation; network structure; small-world effect Information 2013, 4 399 1. Introduction Open innovation will become mainstream in future development of technology and business. Moreover, enterprises that can successfully implement open innovation will get prosperity and development in the new era. Chesbrough [1,2] put forward open innovative logical thinking, which means combining external creativity, ideas and knowledge with internal research and development. He believed that open innovation is inevitably becoming a new way of technology renovation and making profits at present and in the future [1,2]. With the speed acceleration of new knowledge and rapid spread and communication of professional knowledge globally, the potential creativity and ideas must be utilized soon, otherwise the good opportunity will soon disappear. Some companies have made a lot of long-term investment on research and development. However, finally they realized that the projects they had discarded owned big business interests. The most typical example is the Xerox Corporation. Xerox developed numerous computer hardware and software technologies, but a lot of items did not get much attention, such as Ethernet and Graphical User Interface [1]. At that time, the main business of Xerox focused on high-speed copying devices and printers, and these two technologies were thought of as unworthy and discarded in the company. However, at the same time, the two technologies were utilized and commercialized by other companies to get great profits, for example, Apple Computer and Microsoft both using GUI technology in their operating system. In recent years, some international companies also begin to formulate some policies to promote the open innovation. For example, if an idea or a thought cannot be adopted in the internal company in three years, the idea would be sold to other companies even the direct competitor, in order to prevent the potential idea becoming a lost opportunity and being buried inside the company. The practice of a lot of companies to explore open innovation has proved that external technology can fill the blank of the internal business or technical gap, and technology of the internal organization can explore new business at an external level. Open innovative logical thinking proposed by Chesbroug [1,2] focuses on technological innovation. Then, Chesbrough [3–5] put forward six business modes of open innovation from the fundamental levels to high levels and the implementation model. This paper discusses the open innovation only from the perspective of technological innovation, and the research in this paper only focuses technological innovation. Because the time to propose open innovation is short, it will be a new topic for disciplinary study in China, especially in Technological Economics and Corporate Management [6]. An open innovation network can be divided into many forms according to different node types. The applicants contact network based on patent cooperation is one kind of open innovation network. Patent cooperation and joint patent application are the important forms and achievements of open technological innovation. A patent cooperation network of enterprises provides an important network platform for their open innovation. Whether based on the needs of technology or the needs of market, the expandable range of technology and business in the network features in more practical application. Moreover, the technology and business in the network can be combined with new technology and business in other fields and organizations. Therefore, conducting research on the situation of the patent cooperation network of enterprise and the relationship between network structure, open innovation and performance has both theoretical significance and practical importance. The analysis methods and results of this project can provide empirical data and great help for enterprises and research institutions Information 2013, 4 400 to construct network structure, establish and adjust relationship with network partners and determine the network position to make open innovation strategies. Moreover, the results can help the government to promote the construction of a patent cooperation network and the improvement of this network structure from a macroscopic perspective. To date, much research has been done in the patent network analysis through aspects of patent citation network, patent collaboration network, patent technical themes collaboration network and so forth [7–9]. Social network analysis has received more and more attention in the patent analysis [10]. This is because in the collaboration network there is a “U” relationship between the centrality of inventor structure and the company innovation [11]. Moreover, most of existing literature has focused on the quantitative statistics on the patents but very limited work has been done to address the network structure and its evolution dynamics [10]. The social network analysis can assess the evolution dynamics about the patent network and hence may provide deep insight into the patent network analysis [12–14]. The application of the social network analysis in the patent network will be a major research area in the near future. Therefore, for the first time the social network analysis method is adopted in this paper to empirically investigate the dynamic change process of the network in China. Taking the joint patent data published by State Intellectual Property Office of China from 1985 to 2010 as the sample, the paper analyzes the dynamic evolution and network structure of cooperation network of enterprises. The findings of this work will provide a useful theoretical reference for both the government and enterprises to their innovation strategies. 2. Data Collection and Research Method 2.1. Data Collection and Disposal Patents constitute three categories—patent for invention, patent for utility models and patent for design. Patent for invention shows greater creativity than other two categories. Moreover, the patent in this paper only refers to the patent for invention patent. Patent cooperation between enterprises discussed in this paper only refers to one form, which is joint application for patents of enterprises. The data retrieval was conducted on the net of State Intellectual Property Office. The research targets include the joint application of enterprises (including companies, groups and factories), which belong to patents for invention in mainland China (excluding Hong Kong, Taiwan and Macao). The date of data retrieval was 5 September 2011. The author researched the patents from January 1985 to December 2010 and got 39,351 items of original data. Each patent item shows the information of the publication number, application number, publication date, applicants, classification number, and inventor. The research targets also include the patents of research institutions of enterprise, such as Sinopec Shanghai Research Institute of Petrochemical Technology, and the patents of universities if the university was ranked the third and after the third position in the application, because the author assumed thus patents give the priority to the cooperative patent of enterprises. After being processed with above standards, the sample date account for 36,731 items. The annual growth of cooperative patents and enterprises are shown in Figure 1. Annual announcement of patents in China before 2000 featured in small and stable amounts. However, the Information 2013, 4 401 starting phase of rapid growth is from 2000 to 2004; and the boost phase began in 2005. The situation of annual growth of enterprise is similar to the annual growth of cooperative patents. Until 2010, the enterprises which took part in the